Question

Question #98dd6

Answer 1

`6 * 10^(23)`

Explanation:

You know that one mole of any substance contains exactly `6.022 * 10^(23)` atoms or molecules of that substance - this is known as Avogadro's number.

In your case, you're dealing with a millimole, which represents the `1/1000"th"` part of a mole.

So, if you need `10^3` millimoles to make one mole, it follows that you'd need `10^3` times more molecules of carbon dioxide, `"CO"_2`, to get `6.022 * 10^(23)` molecules of carbon dioxide.

`1color(red)(cancel(color(black)("mmole"))) * (1color(red)(cancel(color(black)("mole"))))/(10^3color(red)(cancel(color(black)("mmoles")))) * (6.022 * 10^(23)"molecules CO"_2)/(1color(red)(cancel(color(black)("mole")))) = 6.022 * 10^(23)"molecules CO"_2`

You need to round this off to one sig fig, the number of sig figs you have for the number of millimoles of `"CO"_2`.

`"no. of molecules of CO"_2 = color(green)(6 * 10^(23))`